def _saslprep_do_mapping(chars):
i = <NUM_LIT:0><EOL>while i < len(chars):<EOL><INDENT>c = chars[i]<EOL>if stringprep.in_table_c12(c):<EOL><INDENT>chars[i] = "<STR_LIT>"<EOL><DEDENT>elif stringprep.in_table_b1(c):<EOL><INDENT>del chars[i]<EOL>continue<EOL><DEDENT>i += <NUM_LIT:1><EOL><DEDENT>
Perform the stringprep mapping step of SASLprep. Operates in-place on a
list of unicode characters provided in `chars`.