docs: def from_string(header_str):
          """
          Reads Header string and returns Header object if header was
          generated by pymatgen.
          Note: Checks to see if generated by pymatgen, if not it is impossible
              to generate structure object so it is not possible to generate
              header object and routine ends
  
          Args:
              header_str: pymatgen generated feff.inp header
  
          Returns:
              Structure object.
          """
          lines = tuple(clean_lines(header_str.split("\n"), False))
          comment1 = lines[0]
          feffpmg = comment1.find("pymatgen")
  
          if feffpmg:
              comment2 = ' '.join(lines[1].split()[2:])
  
              source = ' '.join(lines[2].split()[2:])
              basis_vec = lines[6].split(":")[-1].split()
              # a, b, c
              a = float(basis_vec[0])
              b = float(basis_vec[1])
              c = float(basis_vec[2])
              lengths = [a, b, c]
              # alpha, beta, gamma
              basis_ang = lines[7].split(":")[-1].split()
              alpha = float(basis_ang[0])
              beta = float(basis_ang[1])
              gamma = float(basis_ang[2])
              angles = [alpha, beta, gamma]
  
              lattice = Lattice.from_lengths_and_angles(lengths, angles)
  
              natoms = int(lines[8].split(":")[-1].split()[0])
  
              atomic_symbols = []
              for i in range(9, 9 + natoms):
                  atomic_symbols.append(lines[i].split()[2])
  
              # read the atomic coordinates
              coords = []
              for i in range(natoms):
                  toks = lines[i + 9].split()
                  coords.append([float(s) for s in toks[3:]])
  
              struct = Structure(lattice, atomic_symbols, coords, False,
                                 False, False)
  
              h = Header(struct, source, comment2)
  
              return h
          else:
              return "Header not generated by pymatgen, cannot return header object"