Reference: System Variables:

_result

Value Type

Descriptions

This is a general purpose system variable for holding the results of various commands. Since commands can not return values, those that produce a result store it in this variable. The value of _result therefore changes often and should be used immediately after calling a command that modifies it. If the value of _result is needed sometime later, it should be assigned to a user variable for storage. Commands that use this variable say so in their descriptions. The following is an example adds 200 to the print log:

max( 50, 200 )
print( _result )

The _result variable may be manually reset with the clear command.