Answers

1. Here, we must use the dist package to install setuptools_rust before we do anything else in the setup.py file. We define the parameters for the setup and use the RustExtension object from setuptools_rust, pointing to where the compiled Rust module will be once installed.  
2. When the pip module is installed, the binary Rust file is in the same directory where the Python files are defined for the module. However, directories in that directory are not copied over and, therefore, they will be lost during the installation.
3. A singleton design pattern ensures that all references to a particular class all point to one instance of that class.
4. The adapter pattern is an interface that manages the interaction between two modules. The advantage is the flexibility between the modules. We know where all the interactions are, and if we want to sever the modules, all we need to do is delete the adapter. This enables us to switch modules as and when we need them.
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