def make_qs(n, m=None):
    """Make sympy symbols q0, q1, ...
    
    Args:
        n(int), m(int, optional):
            If specified both n and m, returns [qn, q(n+1), ..., qm],
            Only n is specified, returns[q0, q1, ..., qn].

    Return:
        tuple(Symbol): Tuple of sympy symbols.
    """
    try:
        import sympy
    except ImportError:
        raise ImportError("This function requires sympy. Please install it.")
    if m is None:
        syms = sympy.symbols(" ".join(f"q{i}" for i in range(n)))
        if isinstance(syms, tuple):
            return syms
        else:
            return (syms,)
    syms = sympy.symbols(" ".join(f"q{i}" for i in range(n, m)))
    if isinstance(syms, tuple):
        return syms
    else:
        return (syms,)