Is the Sum of Letters Even or Odd?

Create a function that takes a string and returns True if the sum of the position of every letter in the alphabet is even and False if the sum is odd.

Examples

is_alpha("i'am king")  ➞ True
# 9 + 1 + 13 + 11 + 9 + 14 + 7 = 64 (even)

is_alpha("True") ➞ True
# 20 + 18 + 21 + 5= 64 (even)

is_alpha("alexa") ➞ False
# 1 + 12 + 5 + 24 + 1= 43 (odd)

Notes

• Case insensitive.
• Ignore non-letter symbols.