||Shows a message in large words briefly in the middle of the screen; does tostring() on its argument for convenience.
- str - The string or `hs.styledtext` object to display in the alert
- style - an optional table containing one or more of the keys specified in [hs.alert.defaultStyle](#defaultStyle). If `str` is already an `hs.styledtext` object, this argument is ignored.
- screen - an optional `hs.screen` userdata object specifying the screen (monitor) to display the alert on. Defaults to `hs.screen.mainScreen()` which corresponds to the screen with the currently focused window.
- seconds - The number of seconds to display the alert. Defaults to 2. If seconds is specified and is not a number, displays the alert indefinately.
- a string identifier for the alert.
- The optional parameters are parsed in the order presented as follows:
- if the argument is a table and `style` has not previously been set, then the table is assigned to `style`
- if the argument is a userdata and `screen` has not previously been set, then the userdata is assigned to `screen`
- if `duration` has not been set, then it is assigned the value of the argument
- if all of these conditions fail for a given argument, then an error is returned
- The reason for this logic is to support the creation of persistent alerts as was previously handled by the module: If you specify a non-number value for `seconds` you will need to store the string identifier returned by this function so that you can close it manually with `hs.alert.closeSpecific` when the alert should be removed.
- Any style element which is not specified in the `style` argument table will use the value currently defined in the [hs.alert.defaultStyle](#defaultStyle) table.