code: def get_key(blob, field, code):
      
      try:
          line = blob[np.nonzero(blob[:, 1] == field)[0][0] + 1]
      except IndexError:
          return None
      if line[0] == code:
          try:
              return int(line[1])
          except ValueError:
              return line[1]
      else:
          return None
docs: Given a loaded (n, 2) blob and a field name
      get a value by code.