"ultrasonic.MeasureInMillimeters();" not working

[BigSmoke908]

if i take a variable and give it the value "ultrasonic.MeasureInMillimeters();" the arduino ide says, that this does not exist (exact error message below). I have the library installed and other things like
"ultrasonic.MeasureInCentimeters();" work just fine. I am using version 1.0.0 of this library.

Complete Error Message:
Arduino: 1.8.15 (Windows 10), Board: "Arduino Uno"
C:\Users\PC\Desktop\sketch_jul06a\sketch_jul06a.ino: In function 'void loop()':

sketch_jul06a:42:28: error: 'class Ultrasonic' has no member named 'MeasureInMillimeters'; did you mean 'MeasureInCentimeters'?

centimeters = ultrasonic.MeasureInMillimeters();

                        ^~~~~~~~~~~~~~~~~~~~

                        MeasureInCentimeters

exit status 1

'class Ultrasonic' has no member named 'MeasureInMillimeters'; did you mean 'MeasureInCentimeters'?

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