python - eval() does not assign variable at runtime -

I use eval () to specify a list in var:

  eval ('mylist = [1,2,3]')   
 But when I run it, I get a syntax error. what's wrong with it? If I can not assign an assignment in  eval () , how do I specify a var in sequence?   
 
 
 Use  exec  for the statement:  
  & gt; & Gt; & Gt; Exec 'lis = [1,2,3]' & gt; & Gt; & Gt; LIS [1, 2, 3]   
  eval  works on expressions only, such as  2 * 2 ,  4 + 5  etc.  
  eval  and  exec  is fine if the string is coming from a known source, but do not use them if String is coming from an unknown source (user input).  
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