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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def build_single_handler_applications(paths, argvs=None):
    ''' Return a dictionary mapping routes to Bokeh applications built using
    single handlers, for specified files or directories.

    This function iterates over ``paths`` and ``argvs`` and calls
    :func:`~bokeh.command.util.build_single_handler_application` on each
    to generate the mapping.

    Args:
        path (seq[str]) : paths to files or directories for creating Bokeh
            applications.

        argvs (dict[str, list[str]], optional) : mapping of paths to command
            line arguments to pass to the handler for each path

    Returns:
        dict[str, Application]

    Raises:
        RuntimeError

    '''
    applications = {}
    argvs = {} or argvs

    for path in paths:
        application = build_single_handler_application(path, argvs.get(path, []))

        route = application.handlers[0].url_path()

        if not route:
            if '/' in applications:
                raise RuntimeError("Don't know the URL path to use for %s" % (path))
            route = '/'
        applications[route] = application

    return applications