text: const { expect } = require('chai');
  
  /**
   * @param {number[][]} coordinates
   * @return {boolean}
   */
  let checkStraightLine = function(coordinates) {
    for (let i = 1; i < coordinates.length - 1; i++) {
      const curr = coordinates[i];
      const prev = coordinates[i - 1];
      const next = coordinates[i + 1];
  
      if ((curr[1] - prev[1]) * (next[0] - curr[0]) != (curr[0] - prev[0]) * (next[1] - curr[1])) {
        return false;
      }
    }
  
    return true;
  };
  
  it('check-if-it-is-a-straight-line', () => {
    expect(checkStraightLine([[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]])).to.eq(false);
  });