To-Do
 1. Fractions
+2. Tests
 3. expression as unit's val
+4. Revisar reduce y pasar a map
+5. mk :m recurse down primero
 6. Going multiprocess
 7. Functions! Derivate! Integrate!


import Exun.Pattern
import Exun
umatch "f(g)*g'x","cos(sin(x))*cos(x)"
umatch "h+f*g","sin(x)/cos(x)"
umatch "u*v'x","x*2*cos(x^2)"
umatch("u*v'x","x")
umatch("g(y)+f'x","1+x+y")
umatch("f(x)","sin(x)")
umatch("f(2*x)","sin(2*x)")

aast = {:fcall, "f", [{:fcall, "g", [vari: "x"]}]}
expr = {:fcall, "cos", [{:fcall, "sin", [vari: "x"]}]}
map = %{"g" => {:fcall, "sin", [vari: "x"]}, "g'" => {:fcall, "cos", [vari: "x"]}}