docs: def header_string_from_file(filename='feff.inp'):
          """
          Reads Header string from either a HEADER file or feff.inp file
          Will also read a header from a non-pymatgen generated feff.inp file
  
          Args:
              filename: File name containing the Header data.
  
          Returns:
              Reads header string.
          """
          with zopen(filename, "r") as fobject:
              f = fobject.readlines()
              feff_header_str = []
              ln = 0
  
              # Checks to see if generated by pymatgen
              try:
                  feffpmg = f[0].find("pymatgen")
              except IndexError:
                  feffpmg = False
  
              # Reads pymatgen generated header or feff.inp file
              if feffpmg:
                  nsites = int(f[8].split()[2])
                  for line in f:
                      ln += 1
                      if ln <= nsites + 9:
                          feff_header_str.append(line)
              else:
                  # Reads header from header from feff.inp file from unknown
                  # source
                  end = 0
                  for line in f:
                      if (line[0] == "*" or line[0] == "T") and end == 0:
                          feff_header_str.append(line.replace("\r", ""))
                      else:
                          end = 1
  
          return ''.join(feff_header_str)