 Complete the following phrase:  On these following days, the national flag is flown at half staff, mostly commemorating the deaths of important heroes. At any time, the President of Mexico can issue a decree to have the flag flown at half-staff to honor the death of a person who was a major figure of the Mexican government, Mexican society, the head of state of another nation or a tragic event on a major scale. One example is that on the 19th anniversary of the Mexico City 