title: Trying to install python3 but terminal keeps showing as python 2.7.13
body: <p>I have 2.7.13 on macOS Sierra and I'm trying to upgrade to python3 via</p>
  
  <pre><code>brew install python3
  </code></pre>
  
  <p>everything seems to have went fine except the last part:</p>
  
  <pre><code>==&gt; Installing python3 
  ==&gt; Downloading https://homebrew.bintray.com/bottles/python3-3.6.1.sierra.bottle
  ######################################################################## 100.0%
  ==&gt; Pouring python3-3.6.1.sierra.bottle.tar.gz
  ==&gt; Using the sandbox
  ==&gt; /usr/local/Cellar/python3/3.6.1/bin/python3 -s setup.py --no-user-cfg instal
  ==&gt; /usr/local/Cellar/python3/3.6.1/bin/python3 -s setup.py --no-user-cfg instal
  ==&gt; /usr/local/Cellar/python3/3.6.1/bin/python3 -s setup.py --no-user-cfg instal
  ==&gt; Caveats
  Pip, setuptools, and wheel have been installed. To update them
    pip3 install --upgrade pip setuptools wheel
  
  You can install Python packages with
    pip3 install &lt;package&gt;
  
  They will install into the site-package directory
    /usr/local/lib/python3.6/site-packages
  
  See: http://docs.brew.sh/Homebrew-and-Python.html
  ==&gt; Summary
    /usr/local/Cellar/python3/3.6.1: 3,600 files, 55.8MB
  </code></pre>
  
  <p>after that I type </p>
  
  <pre><code>python
  </code></pre>
  
  <p>and I get </p>
  
  <pre><code>Python 2.7.13 (default, Dec 17 2016, 23:03:43) 
  [GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin
  Type "help", "copyright", "credits" or "license" for more information.
  </code></pre>
  
  <p>I'm pretty new to coding so any help is appreciated!</p>