When we measure code metrics or analyze source code, code normalization is occasionally performed as a preprocessing. Code normalization means removing untargeted program elements, formatting source code, or transforming source code with specific rules. Code normalization makes measurement and analysis results more significant. Existing code normalization mainly targets program elements not influencing program behavior (e.g., code comments and blank lines) or program tokens (e.g., variable names and literals). In this paper, we propose a new code normalization technique targeting program structure. Our proposed technique transforms a complex program statement to simple ones. We call this transformation flattening. By flattening code, we can obtain source code including only simple program statements. As applications of the code flattening, we report how it changes LOC metric and clone detection results.