Syntax
      
      
          
          
            
              
                GetInt64( INPUT property-name AS CHARACTER ) 
               | 
            
          
        
 
      
        
          - property-name
 
          - A CHARACTER expression that denotes the name of the property value
to be retrieved from the JsonObject.
 
        
      
      A
JsonError is raised if:
      
        - 
          property-name is the empty string (""), or is the Unknown value
            (?)
 
        - The property does not exist
 
        - The property value is not a valid JSON integral number
 
        - The property value does not fit into an ABL INT64