def split_params(s):
    """Parameters separated by comma. Returns list of parameters."""
    parts = []
    bracket_level = 0
    current = []
    for c in (s + ','):
        if c == ',' and bracket_level == 0:
            parts.append(''.join(current).strip())
            current = []
        else:
            if c == '(':
                bracket_level += 1
            elif c == ')':
                bracket_level -= 1
            current.append(c)
    return parts