=======================
 seq2seq.awk 
=======================
#!/usr/bin/gawk -f
#
#@ convert protein aminoacid sequence files from 
#@ oneletter to threeletter format and vice versa.
#
# (c) Eiso AB
#
# command line options:
# [-v] mode=3to1   # convert from three to one letter format
# [-v] mode=1to3   # convert from one to three letter format [ABCDE...]
# [-v] mode=1nto3   # convert from one to three letter format [A1/
#
# seq2seq.awk will try to determine the type of file from the first
# field on the first line it encounters. If the first word has either 
# one or 4 or more characters oneletter format will be assumed.
# 
# possible input:
#