def sayHi
     "hi!"
end

def listFiles( dir )
    `ls #{dir}`
end

def getTime( format = "%a %b %d %H:%M:%S %Z %Y" )
   Time.now.strftime( format )
end

def printStuff( first, *args )
    "#{first}, #{args.join(', ')}"
end

# calling a method without parameters
puts sayHi                              # parens are optional
puts sayHi() 

# calling a method with a parameter
puts listFiles( "/" )
puts listFiles "/usr"                   # parens are also optional with parameters

# calling a method with optional paramters
puts getTime                            # optional parameters can be excluded
puts getTime( "%m/%d/%Y %I:%M%p" )

# calling a method with variable length params
puts printStuff(1, "two", 3, "four", 5, "six", 7)
puts printStuff(*(1..10).to_a)