. file [ arg ... ]
       Read commands from file and execute them in the current shell
       environment.

       If file does not contain a slash, or if PATH_DIRS is set, the
       shell looks in the components of $path to find the directory
       containing file.  Files in the current directory are not read
       unless `.' appears somewhere in $path.  If a file named `file.zwc'
       is found, is newer than file, and is the compiled form (created
       with the zcompile builtin) of file, then commands are read from
       that file instead of file.

       If any arguments arg are given, they become the positional
       parameters; the old positional parameters are restored when the
       file is done executing.  However, if no arguments are given, the
       positional parameters remain those of the calling context, and no
       restoring is done.

       If file was not found the return status is 127; if file was found
       but contained a syntax error the return status is 126; else the
       return status is the exit status of the last command executed.
