TypeError: Wrong Number of Arguments

Why This Happens

Python enforces function signatures strictly. When you define def foo(a, b), calling foo(1, 2, 3) fails because there is no parameter for the third argument. A common variant is forgetting that instance methods receive self automatically.

The Problem

class Calculator:
    def add(self, a, b):
        return a + b

calc = Calculator()
result = calc.add(1, 2, 3)

The Fix

class Calculator:
    def add(self, a, b):
        return a + b

calc = Calculator()
result = calc.add(1, 2)

Step-by-Step Fix

1. 1

   Check the function signature

   Look at the function definition to see how many parameters it expects.

2. 2

   Count your arguments

   Count the actual arguments at the call site and match them to the parameters.

3. 3

   Use *args for variable arguments

   If the function needs variable arguments, change the signature to use *args.