In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation.
During sexual reproduction, fertilization of the ovum (n, 23 chromosomes) by the sperm (n, 23 chromosomes) restores the diploid number and creates a zygote (2n, 46) (awww..) that divides and grows by mitosis to form a multicellular human.
The sperm and the ovum are known as gametes (each containing half the genetic information of the parent, created through meiosis). The sperm (being one of approximately 250 million sperm in a typical male ejaculation) travels through the vagina and cervix into the uterus or Fallopian tubes.