HasClass returns a NodeP function that returns true if the HTML node it is passed has a class attribute with the value of the given name, otherwise false.

HasElementName returns a NodeP function that returns true if the HTML node it is passed is an element node with the given name, otherwise false.

InBetween returns the portion of string `s` appearing after the first occurrence of substring `before` (exclusive), assuming it exists, and before the first occurrence of substring `after` (exclusive), if it exists.

IsText returns true if the given HTML node is a text node.

NodeIsAll returns the logical conjunction ("and") of the given predicate functions of HTML nodes.

TrimPast returns the portion of string `s` appearing after the first occurrence of substring `before` (exclusive), assuming it exists.

TrimSince returns the portion of string `s` appearing before the first occurrence of substring `after` (exclusive), if it exists, otherwise the entire string.

Attribute wraps html.Attribute so we can define additional convenience methods.

Node wraps html.Node so we can define additional convenience methods.

NodeP represents a boolean predicate function on HTML nodes.