Description of the illustration plsql_function_source

[ schema. ] function_name
  [ ( parameter_declaration [, parameter_declaration]... ) ] RETURN datatype 
[ sharing_clause ]
  [ { invoker_rights_clause
    | accessible_by_clause
    | default_collation_clause    
    | deterministic_clause
    | parallel_enable_clause
    | result_cache_clause 
    | aggregate_clause
    | pipelined_clause
    | sql_macro_clause
       }...
  ]
{ IS | AS } { [ declare_section ] body 
              | call_spec
            }
  ;