docs: def load_initial(self, streams):
          """Load the initial values for parameters and Wilson coefficients from
          one or several files.
  
          `streams` should be a tuple of file-like objects strings."""
          d = {}
          for stream in streams:
              s = io.load(stream)
              if 'BLOCK' not in s:
                  raise ValueError("No BLOCK found")
              d.update(s['BLOCK'])
          d = {'BLOCK': d}
          C = io.wc_lha2dict(d)
          sm = io.sm_lha2dict(d)
          C.update(sm)
          C = definitions.symmetrize(C)
          self.C_in = C