MustParse turns the given string into a query or panics; for tests or others cases where you know the string is valid.

New parses the given string and returns a query or error if the string is invalid.

"CONTAINS"; used to check if a string contains a certain sub string.

"=".

">".

">=".

"<".

"<=".

Condition represents a single condition within a query and consists of tag (e.g.

Empty query matches any set of tags.

Query holds the query string and the query parser.

Operator is an operator that defines some kind of relation between tag and operand (equality, etc.).