Title: A note on the paper "Contraction mappings in $b$-metric spaces" by Czerwik,
Abstract: In this paper we correct an inaccuracy that appears in the proof of Theorem
1. in Czerwik's article "Contraction mappings in $b$-metric spaces.", Acta
Math. Inform. Univ. Ostraviensis, 1:5--11, 1993.