          source fileName
               Read file fileName and pass the  contents  to  the  Tcl
               interpreter as a sequence of commands to execute in the
               normal fashion.  The return  value  of  source  is  the
               return  value  of  the  last  command executed from the
               file.  If an error occurs in executing the contents  of
               the  file,  then  the  source  command will return that
               error.  If a return command is invoked from within  the
               file, the remainder of the file will be skipped and the
               source command will return  normally  with  the  result
               from  the  return  command.   If fileName starts with a
               tilde, then it is tilde-substituted as described in the
               Tcl_TildeSubst manual entry.
