code: def clean_missing_exponent(pst_filename,clean_filename="clean.pst"):
      
      lines = []
      with open(pst_filename,'r') as f:
          for line in f:
              line = line.lower().strip()
              if '+' in line:
                  raw = line.split('+')
                  for i,r in enumerate(raw[:-1]):
                      if r[-1] != 'e':
                          r = r + 'e'
                      raw[i] = r
                  lines.append('+'.join(raw))
              else:
                  lines.append(line)
      with open(clean_filename,'w') as f:
          for line in lines:
              f.write(line+'\n')
docs: fixes the issue where some terrible fortran program may have
      written a floating point format without the 'e' - like 1.0-3, really?!
  
      Parameters
      ----------
      pst_filename : str
          the pest control file
      clean_filename : str
          the new pest control file to write. Default is "clean.pst"
  
      Returns
      -------
      None