def _camel_to_snake(src_string):
    """Convert camelCase string to snake_case."""
    dst_string = [src_string[0].lower()]
    for c in src_string[1:]:
        if c in ("ABCDEFGHIJKLMNOPQRSTUVWXYZ"):
            dst_string.append("_")
            dst_string.append(c.lower())
        else:
            dst_string.append(c)
    return "".join(dst_string)