def suma(n1=[], n2=[]):
   """
   Sum of two field elements. In this case we have implemented the xor gate by the structure field.

   Parameters:
   n1(vector): field element
   n2(vector): field element

   Returns:
   suma (vector): Sum vector
   """

   suma = []
   for i in range(len(n1)):
      if n1[i] == n2[i]:
         suma += [0]
      else:
         suma += [1]
   return suma