How to use the asteval.make_symbol_table function in asteval

def test_partial_exception(self):
        sym_table = make_symbol_table(sqrt=partial(math.sqrt))

        aeval = Interpreter(symtable=sym_table)

        assert aeval("sqrt(4)") == 2

        # Calling sqrt(-1) should raise a ValueError. When the interpreter
        # encounters an exception, it attempts to form an error string that
        # uses the function's __name__ attribute. Partials don't have a
        # __name__ attribute, so we want to make sure that an AttributeError is
        # not raised.
    
        result = aeval("sqrt(-1)")
        assert aeval.error.pop().exc == ValueError

"test making and using a custom symbol table"

        if HAS_NUMPY:
            def cosd(x):
                "cos with angle in degrees"
                return np.cos(np.radians(x))

            def sind(x):
                "sin with angle in degrees"
                return np.sin(np.radians(x))

            def tand(x):
                "tan with angle in degrees"
                return np.tan(np.radians(x))

            sym_table = make_symbol_table(cosd=cosd, sind=sind, tand=tand)

            aeval = Interpreter(symtable=sym_table)
            aeval("x1 = sind(30)")
            aeval("x2 = cosd(30)")
            aeval("x3 = tand(45)")

            x1 = aeval.symtable['x1']
            x2 = aeval.symtable['x2']
            x3 = aeval.symtable['x3']

            assert_allclose(x1, 0.50,     rtol=0.001)
            assert_allclose(x2, 0.866025, rtol=0.001)
            assert_allclose(x3, 1.00,     rtol=0.001)