def is_negligible_turn(turns: float, tolerance: float) -> bool:
    """Returns True is the number of turns in a gate is close to zero."""
    if isinstance(turns, sympy.Expr):
        if not turns.is_constant():
            return False
        turns = float(turns)
    return abs(_signed_mod_1(turns)) <= tolerance
Returns True is the number of turns in a gate is close to zero.
cirq-core/cirq/transformers/analytical_decompositions/single_qubit_decompositions.py