\@ifmtarg seems to fail detecting an empty parameter
5374
How to check if a macro value is empty or will not create text with plain TeX conditionals?
109812
Issue an error when using empty shell variables
72136
Why is my use of the ?: conditional operator incorrect?
36791
C# 4.0, optional parameters and params do not work together
36270
Nullable type issue with ?: Conditional Operator
56714
String comparison in \ifthenelse
128255
Empty Strings: Why or when is '' equal to ' '?
72622
Does Java support default parameter values?
54143
Why is the default value of the string type null instead of an empty string?
703
What is the best way to test for an empty string with jquery-out-of-the-box?
15867
] inside an optional argument
4332
Why does parameter expansion with spaces without quotes work inside double brackets "[[" but not inside single brackets "["?
89873
PHP: a short cut for isset and !empty?
72740
Invoking methods with optional parameters through reflection
7431
How does ${!#} work in bash to get the last command-line argument?
107114
+ or @ mark after running 'ls -al'
146895
multiple nested wildcard - arguments not applicable