isGreaterThanZero property
      
      bool
      get
      isGreaterThanZero
      
    
    
Returns true if the nullable number is not null and greater than zero.
Example:
num? n1 = 5; n1.isGreaterThanZero; // Returns true
num? n2 = null; n2.isGreaterThanZero; // Returns false
num? n3 = 0; n3.isGreaterThanZero; // Returns false
num? n4 = -3; n4.isGreaterThanZero; // Returns false
Implementation
bool get isGreaterThanZero => this != null && this! > 0;