"""Fixes LaTeX square root expressions in a string by ensuring the argument is enclosed in curly braces.

This function processes a string containing LaTeX square root expressions (`\\sqrt`). It ensures that the argument of each `\\sqrt` is properly enclosed in curly braces. If the argument is not already enclosed in braces, the function adds them. The function handles multiple `\\sqrt` expressions in the string and preserves any surrounding text.

Args:
    string (str): The input string containing LaTeX square root expressions.

Returns:
    str: The modified string with all `\\sqrt` arguments properly enclosed in curly braces.

Examples:
    >>> fix_sqrt('\\sqrtx')
    '\\sqrt{x}'
    >>> fix_sqrt('abc\\sqrtxdef')
    'abc\\sqrt{x}def'
    >>> fix_sqrt('abc\\sqrt{x}def\\sqrty')
    'abc\\sqrt{x}def\\sqrt{y}'
"""