V FASTA =
|‘>Rosetta_Example_1
  THERECANBENOSPACE
  >Rosetta_Example_2
  THERECANBESEVERAL
  LINESBUTTHEYALLMUST
  BECONCATENATED’

F fasta_parse(infile_str)
   V key = ‘’
   V val = ‘’
   [(String, String)] r
   L(line) infile_str.split("\n")
      I line.starts_with(‘>’)
         I key != ‘’
            r [+]= (key, val)
         key = line[1..].split_py()[0]
         val = ‘’
      E I key != ‘’
         val ‘’= line
   I key != ‘’
      r [+]= (key, val)
   R r

print(fasta_parse(FASTA).map((key, val) -> ‘#.: #.’.format(key, val)).join("\n"))