# Source: https://docs.datadoghq.com/security/code_security/static_analysis/static_analysis_rules/python-best-practices/special-methods-arguments.md

---
title: ensure special methods have the correct arguments
description: Datadog, the leading service for cloud-scale monitoring.
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  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > ensure special methods have the correct arguments
---

# ensure special methods have the correct arguments

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## Metadata{% #metadata %}

**ID:** `python-best-practices/special-methods-arguments`

**Language:** Python

**Severity:** Error

**Category:** Best Practices

## Description{% #description %}

For all special methods for a class (`__add__`, `__sub__`, and more) make sure the method has the correct number of arguments.

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```python
class GFG:
  
    def __init__(self, val):
        self.val = val
          
    def __next__(self, val2, val3): # invalid, we should have only one argument.
        return GFG(self.val + val2.val)
```

```python
class GFG:
  
    def __init__(self, val):
        self.val = val
          
    def __add__(self, val2, val3): # we should have only two arguments.
        return GFG(self.val + val2.val)
```

## Compliant Code Examples{% #compliant-code-examples %}

```python
class GFG:
  
    def __init__(self, val):
        self.val = val
          
    def __add__(self, val2):
        return GFG(self.val + val2.val)
```
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