With assignment operators, comparisons and booleans use whitespace on either side:

my_variable = 5
if my_variable > 10 and my_variable < 20: 
    pass

Do not use whitespace when assigning a default value in a function signature or when calling a function with keyword arguments:

def my_function(my_var=10):
    pass
my_function(my_var=20)

Do not use whitespace on the internal side of brackets, parentheses, etc.

Do not use whitespace before commas, colons and semicolons; but use whitespaces after commas, colons and semicolons.

4 spaces, avoid <tab> characters.
Python3 programs won't run if tabs and spaces are mixed together. Tabs can lead to issues, so please avoid them.

• Surround top-level functions and classes with two blank lines

  class MyFirstClass:
    pass
  
  
  class MySecondClass:
    pass
  
  
  def top_level_function():
    pass

• Surround methods inside classes with a single blank line

  class MyClass: 
     def first_method(self): 
        pass
  
     def second_method(self): 
        pass

The most commonly suggested maximum line length is 79 characters.
If not possible to comply with this rule, please use line breaks responsibly:

• strings can use parentheses:

  my_long_string = ("string string string string "
                    "string string string string "
                    "string string string string ")

• imports can use parentheses:

  from module import (
     function1, function2, function3
  )

• math operations on multiple lines want the operator on the next line:

  total = (first 
           + second 
           * third)