isWorkspace( name )
    Returns a boolean indicating whether a specified workspace exists.

    Parameters
    ----------
    name: string|RegExp
        Workspace name or a regular expression.

    Returns
    -------
    bool: boolean
        Boolean indicating whether a workspace exists.

    Examples
    --------
    > isWorkspace( 'base' )
    true
    > isWorkspace( /^presentation/ )
    <boolean>

    See Also
    --------
    workspace, workspaces