LAMPTEY ALIAS NKPA v. FANYIE AND OTHERS Evidence—Onus of proof—Facts—Burden of producing evidence on particular issue or fact—Nature of burden on plaintiff and defendant—Plaintiffs claiming agricultural tenancies granted them by defendant abusa rather than abunu as claimed by defendant—Whether burden on plaintiffs to produce requisite evidence shifting—Whether an alleged custom presuming abusa can discharge plaintiff from burden—Plaintiff’s evidence establishing dealings with defendant on abunu terms—Defendant leading evidence to establish abunu—Whether agreement between parties abunu or abusa.