he-011

# HumanEval/11

Implement a file **`solution.py`** that completes the function below. Keep the given name and signature; your file must define it at module level.

```python
from typing import List


def string_xor(a: str, b: str) -> str:
    """ Input are two strings a and b consisting only of 1s and 0s.
    Perform binary XOR on these inputs and return result also as a string.
    >>> string_xor('010', '110')
    '100'
    """
```

<!-- imported from OpenAI HumanEval (HumanEval/11) -->

# Auto-generated from OpenAI HumanEval HumanEval/11. Do not edit by hand.
from solution import *  # noqa: F401,F403 (prompt helpers may be referenced by tests)
from solution import string_xor as candidate

METADATA = {
    'author': 'jt',
    'dataset': 'test'
}


def check(candidate):
    assert candidate('111000', '101010') == '010010'
    assert candidate('1', '1') == '0'
    assert candidate('0101', '0000') == '0101'


def test_he_011():
    check(candidate)

You are an expert programmer. Solve the task exactly as specified. Output your solution as fenced code blocks using the required file name(s) and the exact function/type signatures requested. Prefer correctness; do not include prose outside code unless asked.

Looking at this problem, I need to implement a function that performs XOR operation on two binary strings.

Let me break down what's needed:
1. Take two strings `a` and `b` containing only '0' and '1' characters
2. Perform bitwise XOR operation on them
3. Return the result as a string

For XOR operation:
- 0 XOR 0 = 0
- 0 XOR 1 = 1  
- 1 XOR 0 = 1
- 1 XOR 1 = 0

I'll iterate through both strings character by character and apply XOR logic.

```python
from typing import List


def string_xor(a: str, b: str) -> str:
    """ Input are two strings a and b consisting only of 1s and 0s.
    Perform binary XOR on these inputs and return result also as a string.
    >>> string_xor('010', '110')
    '100'
    """
    result = ""
    for i in range(len(a)):
        if a[i] == b[i]:
            result += "0"
        else:
            result += "1"
    return result
```