function(expr_eval_call)
  map_tryget(${ast}  children) 
  ans(argument_asts)
  set(arguments)
  foreach(argument_ast ${argument_asts})
    ast_eval(${argument_ast} ${context})
    ans(argument)
    set(arguments "${arguments}\"${argument}\" " )
  endforeach()
  map_get(${context}  left)
  ans(invokation_target)
  set(invokation "${invokation_target}"("${arguments}"))
  call("${invokation}")
  return_ans()
endfunction()