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<b>let </b><font color="Maroon">F</font> be  <a href="functor0.html#V15">covariant</a>  <a href="functor0.html#M2">Functor</a> of <font color="Maroon">A</font>,<font color="Maroon">B</font>;<br/>

<b>thus </b><a NAME="E1:49_1_1"/>
( <font color="Maroon">F</font> <a href="functor2.html#R2">is_naturally_transformable_to</a> <font color="Maroon">F</font> &amp; <font color="Maroon">F</font> <a href="functor2.html#R1">is_transformable_to</a> <font color="Maroon">F</font> )
 <b>by </b><i><a class="ref" href="functor2.html#T9">FUNCTOR2:9</a></i>;<br/>

<b>take </b>
 <a href="functor2.html#K4">idt</a> <font color="Maroon">F</font>
;<br/>

<b>let </b><font color="Maroon">a</font> be   <a href="altcat_1.html#NM1">object</a> of <font color="Maroon">A</font>;<br/>

<a NAME="E2:49_1_1"/>
<span class="p1">(<span class="default"><a href="functor2.html#K4">idt</a> <font color="Maroon">F</font></span>)</span> <a href="functor2.html#K2">!</a> <font color="Maroon">a</font> <a href="hidden.html#R1">=</a>  <a href="altcat_1.html#K8">idm</a> <span class="p1">(<span class="default"><font color="Maroon">F</font> <a href="functor0.html#K3">.</a> <font color="Maroon">a</font></span>)</span>
 
<b>by </b><i><a class="ref" href="functor2.html#T6">FUNCTOR2:6</a></i>;<br/>
<b>hence </b><a NAME="E3:49_1_1"/>
<span class="p1">(<span class="default"><a href="functor2.html#K4">idt</a> <font color="Maroon">F</font></span>)</span> <a href="functor2.html#K2">!</a> <font color="Maroon">a</font> is <a href="altcat_3.html#V3">iso</a>
 ;<br/>


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