19if (!function_exists(__NAMESPACE__ . 
'\\cosh')) {
 
   20    function cosh($complex): Complex
 
   22        $complex = Complex::validateComplexArgument($complex);
 
   24        if ($complex->isReal()) {
 
   25            return new Complex(\cosh($complex->getReal()));
 
   29            \cosh($complex->getReal()) * \cos($complex->getImaginary()),
 
   30            \sinh($complex->getReal()) * \sin($complex->getImaginary()),
 
An exception for terminatinating execution or to throw for unit testing.