BMI calculator example (#130)

bmi_calculator/lib/bmi_calculator.dart

@@ -0,0 +1,9 @@
+import 'dart:math';
+
+import 'package:bmi_calculator/body_model.dart';
+
+// I've used weight/height^2 (kg/m^2)
+// You can expand this logic
+double calculateBMI({required BodyModel bodyModel}) {
+  return (bodyModel.weight) / pow(bodyModel.height / 100, 2);
+}