As a consumer I need the concat and concat_ws function definitions with matching signatures in line with http://www.cloudera.com/documentation/archive/impala/2-x/2-0-x/topics/impala_string_functions.html

concat:
concat(string a, string b...)
Purpose: Returns a single string representing all the argument values joined together.
Return type: string

Usage notes: concat() and concat_ws() are appropriate for concatenating the values of multiple columns within the same row, while group_concat() joins together values from different rows.

concat_ws:
concat_ws(string sep, string a, string b...)
Purpose: Returns a single string representing the second and following argument values joined together, delimited by a specified separator.
Return type: string

Usage notes: concat() and concat_ws() are appropriate for concatenating the values of multiple columns within the same row, while group_concat() joins together values from different rows.