def freeze(plugins_directory):
<EOL>package_versions = []<EOL>for plugin_path_i in plugins_directory.dirs():<EOL><INDENT>try:<EOL><INDENT>plugin_metadata = yaml.load(plugin_path_i<EOL>.joinpath('<STR_LIT>').bytes())<EOL>if plugin_path_i.name != plugin_metadata['<STR_LIT>']:<EOL><INDENT>continue<EOL><DEDENT>package_versions.append((plugin_metadata['<STR_LIT>'],<EOL>plugin_metadata['<STR_LIT:version>']))<EOL><DEDENT>except:<EOL><INDENT>continue<EOL><DEDENT><DEDENT>return ['<STR_LIT>' % v for v in package_versions]<EOL>
Parameters
----------
plugins_directory : str
    Path to MicroDrop user plugins directory.

Returns
-------
list
    List of package strings corresponding to installed plugin versions.