How to tell which function is variadic using SHOW FUNCTIONS?

[eladitzhakian]

With the current output, there's no way to differentiate between a variadic function with N arguments and a function with a single argument.

Example SHOW FUNCTIONS output:

Function | Return Type |  Argument Types  | Function Type | Deterministic |             Description
----------+-------------+------------------+---------------+---------------+--------------------------------------
 concat   | array(E)    | E, array(E)      | scalar        | true          | Concatenates an element to an array
 concat   | array(E)    | array(E)         | scalar        | true          | Concatenates given arrays
 concat   | array(E)    | array(E), E      | scalar        | true          | Concatenates an array to an element
 concat   | char(u)     | char(x), char(y) | scalar        | true          | Concatenates given character strings
 concat   | varbinary   | varbinary        | scalar        | true          | concatenates given varbinary values
 concat   | varchar     | varchar          | scalar        | true          | Concatenates given strings

Is there a way I could programmatically tell a function is variadic? Or is this actually a feature request? 😅