missing-format-argument-key / W1303

Message emitted:

Missing keyword argument %r for format string

Description:

Used when a PEP 3101 format string that uses named fields doesn't receive one or more required keywords.

Problematic code:

print("My name is {first} {last}".format(first="John"))  # [missing-format-argument-key]

Correct code:

print("My name is {first} {last}".format(first="John", last="Wick"))

Related links:

• PEP 3101

• Custom String Formatting

Created by the string checker.