material 2 Autocomplete: select option : <p>I want to call a function when an option is selected.
After some search it seem that i have to use :</p>

<p>property <strong>optionSelections</strong> of  <strong>MdAutocompleteTrigger</strong></p>

<p>In the documentation :
<a href="https://material.angular.io/components/component/autocomplete" rel="noreferrer">https://material.angular.io/components/component/autocomplete</a>
<em>optionSelections
Stream of autocomplete option selections.</em></p>

<p>I dont understand that , what is a stream, how to implement this ?</p>
