Trailing commas in "command" syntax?

[exelotl]

Hey! Currently in Nim the "command" syntax is one of the only cases in which 
trailing commas are not allowed.
    
    
    foo 10,
      20,
      30,
    
    # Error: invalid indentation
    
    
    Run

I was wondering if this could be lifted in the future, or if there's a reason 
for it (difficult to parse, introduces ambiguity, etc.)