The patterns used by [ServeMux] allow multiple spaces matching

pkg unicode, var Other_Lowercase *RangeTable
pkg unicode, var Other_Math *RangeTable
pkg unicode, var Other_Uppercase *RangeTable
pkg unicode, var P *RangeTable
pkg unicode, var Pattern_Syntax *RangeTable
pkg unicode, var Pattern_White_Space *RangeTable
pkg unicode, var Pc *RangeTable
pkg unicode, var Pd *RangeTable
pkg unicode, var Pe *RangeTable
pkg unicode, var Pf *RangeTable

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client or server to have an empty Content-Length header.
This behavior is controlled by the `httplaxcontentlength` setting.

Go 1.22 changed the behavior of ServeMux to accept extended
patterns and unescape both patterns and request paths by segment.
This behavior can be controlled by the
[`httpmuxgo121` setting](/pkg/net/http/#ServeMux).

Go 1.22 added the [Alias type](/pkg/go/types#Alias) to [go/types](/pkg/go/types)