lte(other: any): Series {
    return this.where(other, (a, b) => a <= b);
  }
Less than or equal to of `Series` and other, element wise

pandas equivalent: Series <= val

@param {Series|Array|List|number|string} other
   Other `Series` or scalar value to check for less than or equal to

@returns {Series}

@example
const ds = new Series([1, 2, 3], {name: 'Test name'})

// Returns Series([false, false, false])
ds.lte(1);

// Returns Series([false, false, true])
ds.lte(new Series([0, 2, 4]));

// Returns Series([false, false, true])
ds.lte(Immutable.List([0, 2, 5]));

// Returns Series([false, false, true])
ds.lte([0, 2, 5]);