.\"determine whether or not a given variable is an error code
.TH errorp 3
 
.SH NAME
errorp() - determine whether or not a given variable is an error code
 
.SH SYNOPSIS
int errorp(mixed arg);
 
.SH DESCRIPTION
Returns 1 if `arg' is an integer that is an error code.  
.PP
Eventually efuns will be modified to return standard error codes so that 
code like this will be possible: 
.PP
 if (errorp(result = efun_call())) printf("error = %d\n", result); 
.PP
Will also be a perror(result) efun to return error string that goes with 
a particular error integer.