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!


{:integ,
    {:mult,
        {:suma,
            {:suma, 
                {:vari, "x"},
                {:mult, 
                    {:numb, 2}, 
                    {:divi, 
                        {:elev, 
                            {:vari, "x"}, 
                            {:numb, 3}
                        }, 
                        {:numb, 3}
                    }                
                }
            },
            {:divi, 
                {:elev, 
                    {:vari, "x"}, 
                    {:numb, 3}
                }, 
                {:numb, 3}
            }
        },
        {:deriv,
            {:elev, 
                {:suma, 
                    {:numb, 1}, 
                    {:elev, 
                        {:vari, "x"}, 
                        {:numb, 2}
                    }
                }, 
                {:numb, -1}
            },
           {:vari, "x"}
        }
    }
}