Fixed #34140 -- Reformatted code blocks in docs with blacken-docs.

docs/howto/custom-model-fields.txt

@@ -162,12 +162,12 @@ behave like any existing field, so we'll subclass directly from
 
     from django.db import models
 
-    class HandField(models.Field):
 
+    class HandField(models.Field):
         description = "A hand of cards (bridge style)"
 
         def __init__(self, *args, **kwargs):
-            kwargs['max_length'] = 104
+            kwargs["max_length"] = 104
             super().__init__(*args, **kwargs)
 
 Our ``HandField`` accepts most of the standard field options (see the list
@@ -259,10 +259,10 @@ we can drop it from the keyword arguments for readability::
 
     from django.db import models
 
-    class HandField(models.Field):
 
+    class HandField(models.Field):
         def __init__(self, *args, **kwargs):
-            kwargs['max_length'] = 104
+            kwargs["max_length"] = 104
             super().__init__(*args, **kwargs)
 
         def deconstruct(self):
@@ -277,6 +277,7 @@ such as when the default value is being used::
 
     from django.db import models
 
+
     class CommaSepField(models.Field):
         "Implements comma-separated storage of lists"
 
@@ -288,7 +289,7 @@ such as when the default value is being used::
             name, path, args, kwargs = super().deconstruct()
             # Only include kwarg if it's not the default
             if self.separator != ",":
-                kwargs['separator'] = self.separator
+                kwargs["separator"] = self.separator
             return name, path, args, kwargs
 
 More complex examples are beyond the scope of this document, but remember -
@@ -326,7 +327,6 @@ no-op ``AlterField`` operations.
 For example::
 
     class CommaSepField(models.Field):
-
         @property
         def non_db_attrs(self):
             return super().non_db_attrs + ("separator",)
@@ -353,6 +353,7 @@ reference it::
     class CustomCharField(models.CharField):
         ...
 
+
     class CustomTextField(models.TextField):
         ...
 
@@ -397,9 +398,10 @@ subclass ``Field`` and implement the :meth:`~Field.db_type` method, like so::
 
     from django.db import models
 
+
     class MytypeField(models.Field):
         def db_type(self, connection):
-            return 'mytype'
+            return "mytype"
 
 Once you have ``MytypeField``, you can use it in any model, just like any other
 ``Field`` type::
@@ -419,10 +421,10 @@ For example::
 
     class MyDateField(models.Field):
         def db_type(self, connection):
-            if connection.vendor == 'mysql':
-                return 'datetime'
+            if connection.vendor == "mysql":
+                return "datetime"
             else:
-                return 'timestamp'
+                return "timestamp"
 
 The :meth:`~Field.db_type` and :meth:`~Field.rel_db_type` methods are called by
 Django when the framework constructs the ``CREATE TABLE`` statements for your
@@ -442,7 +444,8 @@ sense to have a ``CharMaxlength25Field``, shown here::
     # This is a silly example of hard-coded parameters.
     class CharMaxlength25Field(models.Field):
         def db_type(self, connection):
-            return 'char(25)'
+            return "char(25)"
+
 
     # In the model:
     class MyModel(models.Model):
@@ -460,7 +463,8 @@ time -- i.e., when the class is instantiated. To do that, implement
             super().__init__(*args, **kwargs)
 
         def db_type(self, connection):
-            return 'char(%s)' % self.max_length
+            return "char(%s)" % self.max_length
+
 
     # In the model:
     class MyModel(models.Model):
@@ -481,10 +485,10 @@ need the foreign keys that point to that field to use the same data type::
     # MySQL unsigned integer (range 0 to 4294967295).
     class UnsignedAutoField(models.AutoField):
         def db_type(self, connection):
-            return 'integer UNSIGNED AUTO_INCREMENT'
+            return "integer UNSIGNED AUTO_INCREMENT"
 
         def rel_db_type(self, connection):
-            return 'integer UNSIGNED'
+            return "integer UNSIGNED"
 
 .. _converting-values-to-python-objects:
 
@@ -522,15 +526,17 @@ instances::
     from django.db import models
     from django.utils.translation import gettext_lazy as _
 
+
     def parse_hand(hand_string):
         """Takes a string of cards and splits into a full hand."""
-        p1 = re.compile('.{26}')
-        p2 = re.compile('..')
+        p1 = re.compile(".{26}")
+        p2 = re.compile("..")
         args = [p2.findall(x) for x in p1.findall(hand_string)]
         if len(args) != 4:
             raise ValidationError(_("Invalid input for a Hand instance"))
         return Hand(*args)
 
+
     class HandField(models.Field):
         # ...
 
@@ -569,8 +575,9 @@ For example::
         # ...
 
         def get_prep_value(self, value):
-            return ''.join([''.join(l) for l in (value.north,
-                    value.east, value.south, value.west)])
+            return "".join(
+                ["".join(l) for l in (value.north, value.east, value.south, value.west)]
+            )
 
 .. warning::
 
@@ -653,7 +660,7 @@ as::
         def formfield(self, **kwargs):
             # This is a fairly standard way to set up some defaults
             # while letting the caller override them.
-            defaults = {'form_class': MyFormField}
+            defaults = {"form_class": MyFormField}
             defaults.update(kwargs)
             return super().formfield(**defaults)
 
@@ -680,7 +687,7 @@ For example::
         # ...
 
         def get_internal_type(self):
-            return 'CharField'
+            return "CharField"
 
 No matter which database backend we are using, this will mean that
 :djadmin:`migrate` and other SQL commands create the right column type for