NoSQL operator: deptable

Assess functional dependency between two table columns.

Usage: deptable [options] column_1 column_2

Options:
    --help (-h)
      Print this help info.

Notes:

Takes two column names and an input table and tries to work-out
whether there is a so called ``functional dependency'' between
the two. The second column is said to be functionally-dependent
on the first column when for each value in the former there is
only one value in the latter.

If column_2 is found to be functionally-dependent upon column_1,
then 'true' is printed to STDOUT and a return-code 0 is returned.
Otherwise the return-code is 1 and 'false' is printed.

The higher the number of records in the input table, the more
reliable the test is.