def _functions(expr, x):
    from sympy import Function
    return set(e.func for e in expr.atoms(Function) if x in e.free_symbols)
Building an empty bundle must be an error. Creating an
dataset/ETHPy150Open sympy/sympy/sympy/integrals/meijerint.py/_functions--crossover with--dataset/ETHPy150Open miracle2k/webassets/tests/test_bundle_build.py/TestBuildVarious.test_empty_bundles