The use of operators pairs ( =+ or =-) where the reversed, single operator was meant (+= or -=) will run fine, but not produce the expected results.

This rule raises an issue when =+ or =- is used without any spacing between the two operators and when there is at least one whitespace character after.

Noncompliant Code Example

target = -5
num = 3

target =- num  # Noncompliant; target = -3. Is that really what's meant?
target =+ num # Noncompliant; target = 3

Compliant Solution

target = -5
num = 3

target = -num  # Compliant; intent to assign inverse value of num is clear
target += num