You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: polygonNormalAngle.m
    path of file: ./repos/matGeom/matGeom/polygons2d
    
    the code of the file until where you have to start completion: function theta = polygonNormalAngle(poly, inds)
%POLYGONNORMALANGLE Normal angle at each vertex of a polygon.
%

    
function theta = polygonNormalAngle(poly, inds)
%POLYGONNORMALANGLE Normal angle at each vertex of a polygon.
%
%   THETA = polygonNormalAngle(POLY);
%   where POLY is a N-by-2 array representing vertex coordinates, computes
%   the normal angle at each vertex of the polygon. THETA is a N-by-1 array
%   containing numeric values between -PI and +PI. The result depend