src/Interval.php
public function setLower($lower): self
    {
        // if $lower is not a number, short-circuit
        if ( ! is_numeric($lower)) {
            throw new InvalidArgumentException(
                __METHOD__ . "() expects parameter one, lower, to be a number"
            );
        }
        
        $this->lower = +$lower;
        
        return $this;
    }
public function setLower($lower): self
    {
        // if $lower is not a number, short-circuit
        if ( ! is_numeric($lower)) {
            throw new InvalidArgumentException(
                __METHOD__ . "() expects parameter one, lower, to be a number"
            );
        }
        
        $this->lower = +$lower;
        
        return $this;
    }
Sets the interval's lower value

@param   int|float  $lower
@return  self
@throws  InvalidArgumentException  if $lower is not a number
@since   0.1.0