question: gets the key of the parameter . concode_field_sep BoundValue _valueBinding concode_elem_sep String _value concode_elem_sep String _key concode_field_sep String getValue concode_elem_sep String getValue concode_elem_sep void setValueBinding concode_elem_sep String _getString concode_elem_sep void setValue concode_elem_sep Object clone concode_elem_sep BoundValue getRawValue concode_elem_sep void setKey
target: String function ( ) { return _key ; }