portp

portp( 
g_value 
) 
=> t / nil

Checks if an object is an input or output port.

The suffix p is usually added to the name of a function to indicate that it is a predicate function.

g_value

A data object.

`t`	If g_value is an input or output port, whose type name is `port`.
`nil`	If g_value is not an input or output port.

portp( piport )    
=> t
portp( 3.0 )       
=> nil