thing2 is a word or list and if MEMBERP with these inputs would output TRUE, then MEMBER outputs the portion of
thing2 from the first instance of
thing1 to the end.
If MEMBERP would output FALSE, then MEMBER outputs the empty word or list according to the type of
It is an error for
thing2 to be an array.
SHOW MEMBER "b [a b c d][b c d]
SHOW MEMBER "c [a b c d][c d]
SHOW MEMBER "b "abba"bba