Optionaldeclaration: DeclarationReadonlyfileNote: This is not serialized. It exists for sorting by declaration order, but
should not be needed when deserializing from JSON.
Will be set to Infinity if the ID was deserialized from JSON.
ReadonlyqualifiedNote: This is not serialized. It exists to support detection of the differences between
symbols which share declarations, but are instantiated with different type parameters.
This will be NaN if the symbol reference is not transient.
Note: This can only be non-NaN if pos is finite.
This exists so that TypeDoc can store a unique identifier for a
ts.Symbolwithout keeping a reference to thets.Symbolitself. This identifier should be stable across runs so long as the symbol is exported from the same file.