title: How to know whether a function is continuous with sympy?
body: <p>I need to define a function that checks if the input function is continuous at a point with sympy.</p>
  
  <p>I searched the sympy documents with the keyword "continuity" and there is no existing function for that. 
  I think maybe I should consider doing it with limits, but I'm not sure how.</p>
  
  <pre class="lang-py prettyprint-override"><code>def check_continuity(f, var, a):
      try:
              f = sympify(f)
          except SympifyError:
              return("Invaild input")
          else:
              x1 = Symbol(var, positive = True)
              x2 = Symbol(var, negative = True)
              //I don't know what to do after this
  </code></pre>