code: function getFunctionCallTypeParameterType (func) {
    var type = getFunctionCallType(func)
    if (type.startsWith('function (')) {
      var paramTypes = ''
      var openPar = 1
      for (var x = 10; x < type.length; x++) {
        var c = type.charAt(x)
        if (c === '(') openPar++
        else if (c === ')') openPar--
  
        if (openPar === 0) return paramTypes
  
        paramTypes += c
      }
    } else {
      throw new Error('staticAnalysisCommon.js: cannot extract parameter types from function call')
    }
  }
docs: Extracts the parameter types for a function type signature
  Example:
  function(uint a, uint b) returns (bool) => uint a, uint b
  @func {ASTNode} function call node
  @return {string} parameter signature