"""Aligns the positions of "&" characters in two strings for LaTeX table formatting.

This function takes two strings containing "&" characters and transforms them so that the indices of "&" are aligned. 
It is particularly useful for ensuring proper alignment in LaTeX tables. The function assumes that both strings contain 
the same number of "&" characters. If the "&" characters are not aligned, the function inserts spaces in the appropriate 
positions to align them.

Args:
    str1 (str): The first input string containing "&" characters.
    str2 (str): The second input string containing "&" characters.

Returns:
    Tuple[str, str]: A tuple of two transformed strings with aligned "&" indices.

Raises:
    AssertionError: If the number of "&" characters in `str1` and `str2` is not equal.
"""