Undefined function or variable 'getCurrentTime'.

I get an error: "Undefined function or variable 'getCurrentTime'." while using getCurrentTime function in the MATLAB System Block in Simulink. I tried to invoke the function in the command window. It throws the same error

The code is embedded below:

function y = stepImpl(obj, in)
          v = interp1(obj.clk, obj.usage, getCurrentTime(obj));
          obj.vol = obj.vol + in - v;
          y = obj.vol/(pi * obj.r^2);
end

getCurrentTime is a function that should return the current simulation time in MATLAB System Block

The error I get is the following

[Edwin Joy]

Is getCurrentTime a global function? Or does it belong to a class? If, so which one?