addPrefixToCtx method
Adds a prefix to context using its string forms
Overwrites the previous prefix name if it already exists in context
Implementation
void addPrefixToCtx(String prefixName, URIRef uriRef) {
// Append ':' in the end for consistency and serialization as all keys in
// [ctx] ends with ':' (except for 'BASE' key).
if (!prefixName.endsWith(':')) {
prefixName += ':';
}
ctx[prefixName] = uriRef;
}