##### LM #####
rl ident_pattern /[a-zA-Z_][a-zA-Z_0-9]*/
rl number_pattern /[0-9]+/
lex
ignore /[ \t\n]+/
token id /ident_pattern/
token number /number_pattern/
end
def four_ids
[id id id id]
B: id = construct id "b"
parse Input: four_ids[ stdin ]
for Id: id in Input {
if ( Id == B )
print( B '\n' )
}
##### IN #####
a b c d
##### EXP #####
b