Construct a Statement object.
# S4 method for Statement
initialize(.Object, world, subject, predicate, object,
subjectType = as.character(NA), objectType = as.character(NA),
datatype_uri = as.character(NA))
the Statement object
a World object
a Node object
a Node object
a Node object
the Node type of the subject, i.e. "blank", "uri"
the Node type of the object, i.e. "blank", "uri", "literal"
the datatype URI to associate with a object literal value
the Statement object