def install_tools(dependencies):
tools = getattr(easy.options, "<STR_LIT>", {})<EOL>for dependency in iterutil.flatten(dependencies):<EOL><INDENT>dependency = tools.get(dependency, dependency)<EOL>try:<EOL><INDENT>pkg_resources.require(dependency)<EOL><DEDENT>except pkg_resources.DistributionNotFound:<EOL><INDENT>vsh("<STR_LIT>", "<STR_LIT>", "<STR_LIT>", dependency)<EOL>dependency = pkg_resources.require(dependency)<EOL>easy.info("<STR_LIT>" % (dependency,))<EOL><DEDENT><DEDENT>
Install a required tool before using it, if it's missing.

        Note that C{dependencies} can be a distutils requirement,
        or a simple name from the C{tools} task configuration, or
        a (nested) list of such requirements.