Let $D \subseteq \mathbb{C}$ be an D4995: Open complex disc such that

(i) | $f : D \to \mathbb{C}$ is a D1392: Holomorphic function on $D$ |

(ii) | $\gamma \subseteq C$ is an D5023: Oriented complex curve |

(iii) | $\gamma$ is a D5646: Closed complex curve |

Then
\begin{equation}
\int_{\gamma} f(z) \, d z
= 0
\end{equation}