def p_expression_derivative(p):
'''expression : DERIVATIVE OF expression'''
if s.find('^') != -1:
eq = MathFunctions.formateq(p[3])
else:
eq = str(p[3])
if p[3] is not None:
eq = (str(MathFunctions.derivative(eq, MathFunctions.symbols('x'))))
eq = MathFunctions.reformateq(eq)
p[0] = eq
w = tostring(asciimathml.parse('frac{d}{dx}'))
y = tostring(asciimathml.parse(str(p[3])))
x = tostring(asciimathml.parse(str(p[0])))
print(str(w, "utf-8") + str(y, "utf-8") + "=" + str(x, "utf-8"))
else:
pass
