Botswana

There shall be a President of the Republic of Botswana who shall be the Head of State. (Sec. 30)

(1) Whenever Parliament is dissolved an election shall be held to the office of President in such manner as is prescribed by this section and, subject thereto, by or under an Act of Parliament.
… (Sec. 32)

(1) A person shall be qualified for election as President if, and shall not be qualified unless, he or she-
(a) is a citizen of Botswana by birth or descent;
(b) has attained the age of 30 years; and
(c) is qualified to be elected as a Member of the National Assembly.
(2) Notwithstanding any other law to the contrary, for the purposes of this section and section 39-
(a) the term "citizen by birth" shall be understood to include only those persons who became citizens of Botswana prior to the amendment of the law relating to citizenship by the Citizenship Act;
(b) any person who, although his or her father was a citizen of Botswana at the time of that person's birth, had, by virtue of his or her having been born outside Botswana, to be registered as a citizen of Botswana, under the law relating to citizenship in force at that time, shall be regarded as a citizen by descent. (Sec. 33)

(1) The executive power of Botswana shall vest in the President and, subject to the provisions of this Constitution, shall be exercised by him or her either directly or through officers subordinate to him or her.
… (Sec. 47)