def install_plugin(self, dir, entry_script=None):
self.runtimepath.append(dir)<EOL>if entry_script is not None:<EOL><INDENT>self.command('<STR_LIT>'.format(entry_script), False)<EOL><DEDENT>
Install *Vim* plugin.

:param string dir: the root directory contains *Vim* script
:param string entry_script: path to the initializing script